Sleep

Difficulty: Easy | Acceptance: 87.40% | Paid: No Topics: N/A

Write a function that sleeps for a given number of milliseconds.

• Examples
• Constraints
• Approach 1: Promise with setTimeout
• Approach 2: Async/Await Pattern
• Approach 3: Direct Promise Return

Examples

Example 1

Input: millis = 100
Output: 100
Explanation: It should return a promise that resolves after 100ms. 
let t = Date.now(); 
sleep(100).then(() => console.log(Date.now() - t)); // 100

Example 2

Input: millis = 200
Output: 200
Explanation: It should return a promise that resolves after 200ms.

Constraints

1 <= millis <= 1000

Approach 1: Promise with setTimeout

Intuition Use the Promise constructor with setTimeout to create a delay that resolves after the specified time.

Steps

• Create a new Promise
• Use setTimeout to resolve the promise after millis milliseconds
• Return the promise

import asyncio

async def sleep(millis: int) -> None:
    await asyncio.sleep(millis / 1000)

Complexity

• Time: O(millis) where millis is the sleep time
• Space: O(1)
• Notes: This is the standard way to implement sleep in JavaScript/TypeScript

Approach 2: Async/Await Pattern

Intuition Use async/await syntax to wait for the Promise to resolve before continuing.

Steps

• Define an async function
• Create a Promise with setTimeout
• Await the Promise to ensure the delay
• Return nothing (void)

import asyncio

async def sleep(millis: int) -> None:
    await asyncio.sleep(millis / 1000)

Complexity

• Time: O(millis) where millis is the sleep time
• Space: O(1)
• Notes: Using await makes the code more readable when used in async contexts

Approach 3: Direct Promise Return

Intuition Return a Promise directly without using the async keyword for a more explicit return type.

Steps

• Define a function that returns Promise<void>
• Create a new Promise with setTimeout
• Return the promise directly

import asyncio

async def sleep(millis: int) -> None:
    await asyncio.sleep(millis / 1000)

Complexity

• Time: O(millis) where millis is the sleep time
• Space: O(1)
• Notes: This approach explicitly shows the Promise return type without async sugar